Process ofreducing zinc or spelter from ores



UNITED STATES PATENT O EICE.

(lllRIS'lOllllC JAMES, OF S\\'1\NSlC/\, ENGLAND.

PROCESS o F'REDUClNG ZINC OR SPELTER FROM ORES.

SPECIFICATION forming part of Letters Patent No. 478,110, dated July 5, 1892. Application filed August 18, 1891. Serial No. 403,043. (No specimens.)

To all whom it may concern.-

Be it known that I, CHRISTOPHER Janus, a subject of the Queen of Great Britain and Ireland, residing at Swansea, England, have invented an Improved Process of Reducing Zi no or Spelter from Ores, of which the following is a specification.

This invention relates to an improved method or process of producing metallic zinc from any ores or compounds containing the same, and has for its object the diminution of the usual known calcining, operations, the ,utilization ot'the natural sulphur of the ore to assist or effect reduction, the employment of rererberatory or gas furnaces instead of the costly and troublesome retort-furnaces hitherto used, the greater percentage of metallic zinc covered from the ore, and the better collection of the zinc in a distinct condenser, avoiding the present heavy losses through cracked retorts, impe fect clay connections, and waste of metal in the retort refuse.

In the ordinary methods now in use Zinc ores are calcined till all the zinc present either as carbonate or sulphide is changed to an oxide. This is then mixed with coal or other carbonaceous matter placed in retorts, a large number of which are arrai'iged in the same furnace, and subjected to a great heat. The oxide of zinc termed by the calcination is reduced by the coal added to the charge, as expressed by the equation 9ZnO+U:EAn--l-(7(),. The nine thus reduced to metal is at once volatilized by the heat at which the furnace is Worked and leaves as gas the gaugue of the ore and the uneonsmned coal. This is condensed in the cooler part of the retort and in suitable connections outside the retorts. This process is exceedingly wasteful and expensive. The zinc is only very partially re duced bythe coal and so much zinc is left in the etort refuse that ores containing, a large perjentageotzinccannot beprofitably worked. Enormous losses occur through the cracking and breaking of the clay rctorts, and the process is generally extravagant in labor, coal, and zinc.

In my new process described herein for the first step I calcine only a portion of the ore until all the sulphur is drawn off and all the zinc is oxidized to a high or low degree of oxidation. 'lhis calcined portion I mix with such a portion of raw zinesulphide (blende) as will sutlico when the whole is heated together, as a second step in my process, to reduce the whole of the oxide of zinc in the calcined portiouitself,as wellas thesulphideitself,bytheir mutual reaction to zinc and S0,. The charge of mixed calcined and raw ore as above I wt ,Zuuegas passes, the tubes being surrounded [L h water. in the chamber or tubes the zinc ts condensed and is then ladled out ready for the market.

The reduction as above describcdnvhere the sulphur in the ore is utilized in reduction, is

more natural and perfect than when coal or similar carbonaceous matter is used. The reaction of my method is chemically expressed by the formula iZntH ZnS:3Zn-1fSO that is, two parts, by weight, of zinc oxide mcchani cally mixed with one part of zinc sulphide, when heated together, give all the zinc free and all the sulphur and oxygen combined sulphurous anli vdride.

One great. superiority of this process arises from the collection and comlensation of the zinc being: cllfected in a large, distinct, and. easily-accessible chamber or in an ap iaratns equally open to frequent examinatioii, so that no loss of zinc takes p ace through leakage, while the small amount of oxide of zinc which may be formed by any tree oxygen which can pass into the furnace I collect in suitable tines and chambers to be again used as calei'ned zinc ores. 'lhe expense of workingsuch a furnace will be very small compared to the ordinary retoi"t-l't1rnace, the repairs much less, while the laborand loss of timecaused the breaking, and consequent changing ot daniaged retorts are entirely avoided. I

By my above method of reduction ores containing less than ten per cent. of zinc can be profitably worked, in consequence of the decreased cost following the use, to efiect reduction of the natural sulphur of the ore in lieu of coal, which latter is not only expensive itself, but renders the retort refuse unfit for any after treatment for the recovery of other metals than zinc contained in the ore. By my method the refuse from the retorts or furnace will be in a better condition for further treatment,while very nearly all the zinc originally present in the ore is driven off and ,condenscd.

It is obvious that my process, as far as the utilization of the natural sulphur of the ores to effect the reduction of the oxide of zinc, might be farried on :in the ordinary retorts with some advantage as regards the present system of extreme calcination-and subsequent carbonization for roduction; but a much better advantage would be obtained by the use of reverberatory or gas furnaces, as hereinbefore described.

I do not pretend to claim as novel or unknown the chemical fact that 2Zn0 and ZnS when heated together will produce zinc and S0 7 Having now described my invention, what I claim is A process for the commercial treatment of zinc-sulphide ores, consisting in first calcining a. part of the ore in acalcining-furnace to the form of an oxide, mixing the calcined ore with rather more than half its weight of crude ore, and smelting the same in the hearth of a neutral or slightly-reducing reverberatory furnace until reduced to zinc and 50,, the zinc being volatilized and collected by condensation in a chamber distinct from the fur 

